Students are sometimes proactive and engaged in classroom learning activities, but they are also sometimes only reactive and passive. Recognizing this, in this article I argue that students' classroom engagement depends, in part, on the supportive quality of the classroom climate in which they learn. According to the dialectical framework within self-determination theory, students possess inner motivational resources that classroom conditions can support or frustrate. When teachers find ways to nurture these inner resources, they adopt an autonomy-supportive motivating style. After articulating what autonomy-supportive teachers say and do during instruction, I discuss 3 points: teachers can learn how to be more autonomy supportive toward students; teachers most engage students when they offer high levels of both autonomy support and structure; and an autonomy-supportive motivating style is an important element to a high-quality teacher-student relationship.